1. Field of the Invention
This invention relates in general to a wellbore tool utilized for performing work within a wellbore by converting a chemical pressure source into a force exerted over a distance for operating force actuated downhole tools.
2. Background of the Invention
Prior art wellbore tools have been utilized to provide power for operating and setting downhole tools. One example of such a prior art wellbore tool is a cable conveyed bridge plug for setting within a cased wellbore such as that shown in U.S. Pat. No. 2,637,402, entitled "Pressure Operated Well Apparatus, " invented by R. C. Baker et al., and issued to Baker Oil Tools, Inc. on May 5, 1953. A similar cable conveyed wellbore tool is disclosed in U.S. Pat. No. 2,695,064, entitled "Well Packer Apparatus," invented by T. M. Ragan et al., and issued to Baker Oil Tools, Inc. on Nov. 23, 1954. These patents disclose cable conveyed wellbore tools for setting a bridge plug within a wellbore casing. Both of the cable conveyed wellbore tools include a prior art power charge for providing energy to set the bridge plug within the wellbore casing. These cable conveyed wellbore tools were actuated by the percussion of a firing pin causing a cartridge to explode and ignite the prior art power cartridge, or combustible charge.
Another example of prior art wellbore tool is the wireline conveyed well packer apparatus disclosed in U.S. Pat. No. Re. 25,846, entitled "Well Packer Apparatus," invented by D. G. Campbell, and issued to Baker Oil Tools, Inc. on Apr. 31, 1965. The wireline conveyed well packer apparatus disclosed includes a power charge which is ignited to generate gas for setting the well packer apparatus within a wellbore. The power charge is ignited by passing an electric current down the wireline and exploding an igniter cartridge, which causes a flame to ignite the power charge.
An example of a prior art power charge for use in a wellbore tool to generate gas is a combustion charge disclosed in U.S. Pat. No. 2,640,547, entitled "Gas-Operated Well Apparatus," invented by R. C. Baker et al., and issued to Baker Oil Tools, Inc. on Jun. 2, 1953. The combustion charge is comprised of combustion materials which, when ignited within a wellbore tool disclosed in the patent, will take at least one second for a maximum pressure to be attained within the wellbore tool. This prior art combustion charge includes both a fuel and a self-contained oxygen source. The combustion charge is ignited to generate a pressurized gas which provides a force for setting the gas-operated well apparatus. The combustion charge of the gas-operated well apparatus is ignited by exploding an igniter to start the combustion reaction for burning the combustion charge. The combustion charge, once ignited, burns in a self-sustained combustion reaction to generate the pressurized gas.
Another prior art wellbore tool is the wireline setting tool disclosed in U.S. Pat. No. 2,692,023, entitled "Pressure Operated Subsurface Well Apparatus," invented by M. B. Conrad, and issued to Baker Oil Tools, Inc. on Oct. 19, 1954. The wireline conveyed wellbore tool includes a power charge which is burned in a combustion reaction to generate a pressurized gas. The power charge is ignited by electrically exploding an igniter cartridge which then emits a flame to start the power charge burning. Combustion of the power charge generates pressurized gas having a pressure which provides force for operation of the wireline setting tool to set a downhole tool such as a packer or bridge plug within the wellbore.
Each of the above-referenced patents, U.S. Pat. Nos. 2,640,547, Re. 25,846, 2,695,064, 2,637,402, and 2,692,023, are hereby incorporated by reference as if fully set forth and disclosed herein.
As disclosed in the above-referenced devices, these prior art wellbore tools for converting the chemical components of a power charge into a mechanical force exerted over a distance require at least a separate igniter cartridge for igniting the power charge. Typically, explosive components are used for these prior art igniter materials, such as, for example, gunpowder or lead azide. These types of igniter materials are easily ignited and represent hazards both to operators utilizing these materials in wellbore tools, and to successful completion of wellsite operations. Some of these types of primary ignition or igniter materials are susceptible to ignition from applications of small amounts of electric current, or even discharge of static electricity.
Further, due to the hazards of these igniter materials, special procedures and equipment are required for both transporting and storing prior art igniter materials. Due to the relative ease with which these igniter materials may be ignited, they are typically stored and transported separately from power charge materials to prevent exposure of a large energy source contained within the power charge from such relatively volatile materials included within prior art igniters.